Feng Tang 4df910620b mm: memcg: relayout structure mem_cgroup to avoid cache interference ... 0day reported one -22.7% regression for will-it-scale page_fault2 case [1] on a 4 sockets 144 CPU platform, and bisected to it to be caused by Waiman's optimization (commit bd0b230fe1) of saving one 'struct page_counter' space for 'struct mem_cgroup'. Initially we thought it was due to the cache alignment change introduced by the patch, but further debug shows that it is due to some hot data members ('vmstats_local', 'vmstats_percpu', 'vmstats') sit in 2 adjacent cacheline (2N and 2N+1 cacheline), and when adjacent cache line prefetch is enabled, it triggers an "extended level" of cache false sharing for 2 adjacent cache lines. So exchange the 2 member blocks, while keeping mostly the original cache alignment, which can restore and even enhance the performance, and save 64 bytes of space for 'struct mem_cgroup' (from 2880 to 2816, with 0day's default RHEL-8.3 kernel config) [1]. https://lore.kernel.org/lkml/20201102091543.GM31092@shao2-debian/ Fixes: bd0b230fe1 ("mm/memcg: unify swap and memsw page counters") Reported-by: kernel test robot <rong.a.chen@intel.com> Signed-off-by: Feng Tang <feng.tang@intel.com> Acked-by: Waiman Long <longman@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2020-11-26 09:35:49 -08:00
..
acpi	pci-v5.10-changes	2020-10-22 12:41:00 -07:00
asm-generic	Merge branch 'for-5.10-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu	2020-11-15 08:57:19 -08:00
clocksource
crypto
drm	drm: drm_print.h: fix kernel-doc markups	2020-10-27 11:21:39 +01:00
dt-bindings	ARM: Devicetree updates	2020-10-24 10:44:18 -07:00
keys
kunit	kunit: fix display of failed expectations for strings	2020-11-10 13:45:15 -07:00
kvm	ARM:	2020-10-23 11:17:56 -07:00
linux	mm: memcg: relayout structure mem_cgroup to avoid cache interference	2020-11-26 09:35:49 -08:00
math-emu
media	ARM: SoC platform updates	2020-10-24 10:33:08 -07:00
memory
misc
net	ipv6: Remove dependency of ipv6_frag_thdr_truncated on ipv6 module	2020-11-19 10:49:50 -08:00
pcmcia
ras	mm,hwpoison: introduce MF_MSG_UNSPLIT_THP	2020-10-16 11:11:17 -07:00
rdma	RDMA: Add rdma_connect_locked()	2020-10-28 09:14:49 -03:00
scsi	scsi: libiscsi: Fix NOP race condition	2020-11-16 22:32:50 -05:00
soc	ARM: SoC-related driver updates	2020-10-24 10:39:22 -07:00
sound	ASoC: Fixes for v5.11	2020-11-19 19:56:29 +01:00
target
trace	Just one quick fix for a tracing oops.	2020-11-18 12:06:34 -08:00
uapi	GPIO fixes for the v5.10 series:	2020-11-13 10:55:50 -08:00
vdso
video	gpu: ipu-v3: remove unused functions	2020-10-26 10:42:38 +01:00
xen	xen: branch for v5.10-rc1c	2020-10-25 10:55:35 -07:00